PHANTOM STANDARDS WITH TEMPERATURE-INDEPENDENT AND FIELD-INDEPENDENT RELAXATION RATES FOR MAGNETIC-RESONANCE-IMAGING

RATIONALE AND OBJECTIVES. For use as magnetic resonance imaging refere nce standards, the optimal set of phantoms should cover a wide range o f T-1 values, with each phantom having a T-1 that is stable over time and is independent of temperature and magnetic field strength. To date , no set of phantoms fulfilling these four requirements has been prepa red, In the current work, the construction of such optimal phantom sta ndards is attempted, METHODS. TWO linear gadolinium DTPA polymers are used: the first with relaxivities that are independent of temperature and magnetic field strength, and the second with relaxivities that are independent of magnetic field strength, but have an opposite temperat ure dependence from that of the 1/T-1 of the diamagnetic matrix (agaro se gel or water). Depending on the desired T-1, either one or a combin ation of the two agents is used. RESULTS. Phantom standards were const ructed with 1/T-1 values that are independent of temperature (20-35 de grees C) and magnetic field strength (0.47-1.2 T) over a wide range of 1/T-1 values (greater than or equal to 0.95 s(-1)). Phantom standards prepared in water were found to be stable with respect to 1/T-1 for a t least 18 months. CONCLUSIONS. Stable phantoms standards have been co nstructed covering a wide range of T-1 values, where the T-1 of any pa rticular phantom is independent of temperature and magnetic field stre ngth for magnetic resonance imaging conditions.